Cypress Semiconductor Corp CY7C1668KV18-450BZXC

Overview

CY7C1668KV18 from Cypress Semiconductor is a 144-Mbit (8 M × 18) DDR II+ synchronous SRAM with two-word burst architecture, 2.5-cycle read latency, and 550-MHz clock operation. It features dual echo clocks (CQ/CQ), QVLD data-valid indicator, and PLL-based timing alignment for high-speed memory subsystems in networking and telecom line cards.

For engineers reviewing the CY7C1668KV18 datasheet, CY7C1668KV18 pinout, CY7C1668KV18 application, or CY7C1668KV18 equivalent, key selection criteria include DDR II+ burst timing compliance, HSTL-18 I/O compatibility, 165-ball FBGA mechanical fit, and DOFF-pin configurable latency mode (2.5-cycle vs. 1-cycle).

Technical Context

This SRAM implements a pipelined, synchronous architecture where address and control signals are latched on rising edges of K clock, while write data is registered on both K and K edges. Read data is driven synchronously on both K and K edges, enabling true double-data-rate transfers at up to 1100 MT/s.

The device integrates an internal PLL for precise data placement relative to echo clocks CQ/CQ, supports programmable output impedance via ZQ pin, and provides byte-write select (BWS0/BWS1) for granular 9-bit write control. DOFF pin toggles between DDR II+ (2.5-cycle latency, 550 MHz) and DDR I (1-cycle latency, ≤167 MHz) modes.

Key Specifications

Pinout & Package

Package: 165-ball fine-pitch ball grid array (FBGA), 15 mm × 17 mm × 1.4 mm, RoHS-compliant, Pb-free.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-speed burst SRAM applications.

Compared with CY7C1668AV18-450BZXC, the CY7C1668KV18 delivers +22% bandwidth and flexible latency mode; versus AS7C3256A-15JIN, it enables full DDR II+ system integration but requires clock tree and echo clock routing discipline.

Availability

CY7C1668KV18 is available at Aetrix Electronics and suitable for high-speed packet buffering, telecom line card memory, FPGA-based protocol acceleration, and network processor co-processor memory requiring stable component supply across extended product lifecycles.

Supply support for CY7C1668KV18 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Cypress Semiconductor (now part of Infineon Technologies) is a fabless semiconductor company specializing in high-performance memory, microcontrollers, and connectivity solutions for industrial, automotive, and communications markets.

The CY7C1668KV18 belongs to Cypress's QDR II+/DDR II+ SRAM product line, engineered specifically for deterministic, low-latency, high-bandwidth memory subsystems in networking infrastructure and high-end test equipment.

FAQ

What is the function of the DOFF pin on CY7C1668KV18?

The DOFF pin is an active-low PLL disable input. When asserted LOW, it disables the internal PLL and forces the device into DDR I mode with 1-cycle read latency and maximum 167-MHz operation. When HIGH, the PLL is enabled, supporting DDR II+ mode with 2.5-cycle latency and up to 550-MHz clock frequency. This pin must be pulled up via ≤10 kΩ resistor for normal DDR II+ operation.

How does the ZQ pin affect signal integrity in high-speed designs?

The ZQ pin connects to an external resistor to ground (typically 240 Ω) to calibrate the output driver impedance of DQ, CQ, and CQ pins to 0.2 × RQ (≈48 Ω). This dynamic impedance matching minimizes reflections and ensures consistent signal rise/fall times across process/voltage/temperature variations, directly improving eye diagram margins at 1100 MT/s.

Can CY7C1668KV18 operate without using the echo clocks CQ/CQ?

No - CQ and CQ are mandatory for reliable data capture. The device drives read data edge-aligned with these echo clocks, and QVLD is synchronized to them. Omitting CQ/CQ routing prevents valid data recovery because the SRAM does not provide center-aligned or static timing windows; all read data timing is referenced solely to CQ/CQ edges.

What is the role of BWS0 and BWS1 in byte-write operations?

BWS0 and BWS1 are active-low byte write select inputs that control which 9-bit segment of DQ[17:0] is written during a burst. BWS0 governs DQ[8:0], and BWS1 governs DQ[17:9]. When either is HIGH, the corresponding byte remains unaltered - enabling true partial-word writes without requiring read-modify-write cycles or external masking logic.